1. Field of the Invention
The present invention relates to an image forming apparatus.
Priority is claimed on Japanese Patent Application No. 2009-079787, filed Mar. 27, 2009 and Japanese Patent Application No. 2009-168032, filed Jul. 16, 2009, the contents of which are incorporated herein by reference.
2. Description of Related Art
An image forming apparatus such as a copy machine or a multifunctional device has a function for image-repeat printing. According to the image-repeat printing, an image (original document image) of one sheet of an original document read by a scanner is printed on one sheet of a recording paper a number of times (the number of repeats) designated by a user. Further, according to the image-repeat printing, a variable magnification process is performed with respect to the original document image to generate an image for image-repeat, the image is mapped to a data storage area by the number of repeats to generate a printing image (image-repeat image) corresponding to one sheet of the recording paper, and the image-repeat image is printed on the recording paper. For example, Japanese Patent Application, First Publication No. 2004-248262 discloses one example of the related art for the above-described image-repeat printing.
Further, the image forming apparatus has a function of preview-displaying the printing image on a display in order to check in advance the image to be printed. According to the preview-display, when the original document image is read, reduced images (thumbnail) are generated by reducing the original document image at a predetermined reduction ratio, and the thumbnail images are displayed on the display as a preview image. In general, since the size of the display is smaller than that of the recording paper, after thumbnail images having a size smaller than that of the original document image are generated, the thumbnail images are used for the preview-display. The above preview-display is disclosed in detail in Japanese Patent Application, First Publication No. 2000-078395.
Meanwhile, the preview image in the image-repeat printing is generated by mapping the thumbnail images by the number of repeats such that they are adjacent to each other but do not overlap with each other. That is, in the image-repeat printing, an image-repeat image and a preview image, which are actually provided for printing, have a difference therebetween. That is, the former is generated based on the original document image and the latter is generated based on the thumbnail images obtained by reducing the original document image.
However, when thumbnail images are generated by reducing the original document image at the predetermined reduction ratio, a difference may occur between the preview image and the image-repeat image due to a calculation error in the image forming apparatus. In particular, if the number of repeats is increased, the above difference also increases, so differences between each repeat may occur between the preview image and the image-repeat image. That is, if the size of the thumbnail images includes a calculation error with respect to the size of the original document image, when the thumbnail images are arranged so as to be adjacent to each other without overlapping each other, a part of the preview image may be broken at an end portion thereof or a white space may occur. Due to such a difference between the preview image and the image-repeat image in the image-repeat printing, significant technical problems remain in the image forming apparatus, since the preview image may lose the original quality.